Hi cnfcomp,
Thanks for the post! Being able to sync your device with iTunes is important, and it sounds like you're seeing an Error (-54) on your PC, but you're able to sync with a Mac. I'm happy to offer some assistance.
It sounds like you've done some very thorough troubleshooting, including most of the steps in these resources: If you see an error when you update or restore your iPhone, iPad, or iPod
The resource titled If you see error -54 when you sync with your computer has a few other steps also. Have you tried these yet?
Sync only a small amount of content at a time. Add more content until you see the error again. By doing this, you'll identify the content that causes the issue.
If the issue happens with content from the iTunes Store, delete and then re-download the content. Or, download the content directly to your iPhone, iPad, or iPod touch.
If the content isn't from the iTunes Store, delete and then re-import it from the original source.
This issue might happen when you try to transfer iTunes purchases from your iOS or iPadOS device to your computer. This might also happen when you try to sync with Apple Books, because it uses the same process. If so, there might be a problem with a PDF file saved to the Books app on your iOS device.
To fix the issue, use the Share option in the Books app on your device to email the PDF to yourself. This saves a copy of the PDF in your email account and shares it with the email address you choose, which can be accessed from your computer. Then, remove the PDF file from your device."
I recommend giving these a try if you haven't already. If that doesn't clear things up, use this to Contact Apple Support to look into the issue further.
Have a good one.
